raw_storage_iterator<ForwardIterator, T>

Categories: allocators, iterators, adaptors

Component type: type

Description

In C++, the operator new allocates memory for an object and then
creates an object at that location by calling a constructor. Occasionally,
however, it is useful to separate those two operations. [1] If i is an
iterator that points to a region of uninitialized memory, then you
can use construct to create an object in the location pointed to
by i. Raw_storage_iterator is an adaptor that makes this
procedure more convenient. If r is a raw_storage_iterator, then
it has some underlying iterator i. The expression *r = x is
equivalent to construct(&*i, x).

Returns the iterator's category.
This is a global function, not a member.

New members

These members are not defined
in the Output Iterator requirements,
but are specific to raw_storage_iterator.

Function

Description

raw_storage_iterator(ForwardIterator i)

Creates a raw_storage_iterator whose underlying iterator is i.

raw_storage_iterator& operator=(const T& val)

Constructs an object of ForwardIterator's value type at the
location pointed to by the iterator, using val as the
constructor's argument.

Notes

[1]
In particular, this sort of low-level memory management is used
in the implementation of some container classes.

[2]
Note how assignment through a raw_storage_iterator is implemented.
In general, unary operator* must be defined so that it returns a
proxy object, where the proxy object defines operator= to perform
the insert operation. In this case, for the sake of simplicity, the
proxy object is the raw_storage_iterator itself. That is, *i
returns i, and *i = t is equivalent to i = t. You should not,
however, rely on this behavior. It is an implementation detail,
and it is not guaranteed to remain the same in future versions.